Field of the Invention
Exemplary embodiments of the present invention relate to an electrolytic copper foil, an electric component and a battery including the same, and more particularly, to a low-roughness, high-strength, and high-elongation electrolytic copper foil which has high tensile strength and elongation even after being subjected to high-temperature heat treatment.
Description of the Related Art
As a current collector of a secondary battery, a copper foil is generally used. As the copper foil, a rolling copper foil which is manufactured by rolling working has been mainly used, but manufacturing cost is expensive and it is difficult to manufacture a copper foil having a wide width. Further, the rolling copper foil has reduced adhesion to an active material due to pollution of lubricating oil since the lubricating oil needs to be used at the time of the rolling working, and thus charging and discharging cycle characteristics of the battery may be degraded.
A lithium battery is accompanied by a change in volume at the time of charging and discharging and a heat generation phenomenon due to overcharging. Further, the copper foil should have low surface roughness to improve adhesion to an electrode active material and to make a copper foil substrate be less affected by expansion and contraction of an active material layer during a charging and discharging cycle so as to prevent wrinkle, fracture, and the like from occurring on the copper foil as the current collector. Therefore, a need exists for a high-elongation, high-strength, and low-roughness copper foil which may bear a change in voltage and the heat generation phenomenon of a lithium battery and have excellent adhesion to an active material.
Further, to increase integration of a circuit within a small area to keep pace with high performance, miniaturization, and weight reduction according to a demand for compactness and miniaturization, a demand for micro patterning of a semiconductor mounting substrate or a main board substrate has been increased. When a thick copper foil is used to manufacture a print wiring board having the micro pattern, etching time for forming a wiring circuit is long and side wall verticality of a wiring pattern is reduced. In particular, when a line width of the wiring pattern formed by the etching is narrow, the wiring may be short-circuited. Therefore, to obtain a micro pitch circuit, a thinner copper foil is required. However, due to the required thinner copper foil, which has weak mechanical strength, the occurrence frequency of defects such as wrinkles and bending is increased at the time of manufacturing the printed wiring board.
Further, in a semiconductor packaging substrate, and the like, for tape automated bonding (TAB) which is used in a tape carrier package (TCP), a plurality of terminals of an IC chip are directly bonded to an inner lead which is placed at a device hall located in a center of the product, and in this case, a bonding device is used to make a current instantly flow therein to heat it and apply a constant pressure thereto. Therefore, the inner lead formed by the etching of the electrolytic copper foil is pulled by a bonding pressure and is thus stretched.
Therefore, a low-roughness copper foil which may have a thin thickness, high mechanical strength, and high elongation is required.